First off it irks me Soul Trap is in conjuring, you're not conjuring anything, you're not summoning anything. I have always enjoyed the branch of mysticism because it dealt with entropic and spiritual magic, which I like. I was never a big fan of necromancers, but mysticism,spiritual entropic magic was always my favorite. I don't like elemental mages or necromancers, I always played spiritual mages.

Several spells that I just don't feel they fit in their schools is well of course Soul Trap, that belongs in Mysticism. Second off are the Ward spells which are not restoration spells, they are much more like the dispel spells, and would go into Mysticism.

Read the description: "The school of mysticism includes spells that absorb, reflect, and dispel magic, move objects, sense life, and bind souls."

Conjuration description: "Conjuration is the magic of summoning creatures from other planes, creating magical weapons and armor, and repelling undead creatures. Summoning creatures is particularly useful, providing the spellcaster with an ally in combat"

Alteration: "Alteration is the magic of altering the physical world. It provides many useful effects that can make up for other character weaknesses, for example: Open can be used instead of Security to open locks; Feather can be used if your Strength is too weak; Shield can be used instead of armor. In addition, Water Breathing and Water Walking provide valuable capabilities."

So Mage Skin should go into Mysticism, as well as Telekensis and not into Alteration. And Soul Trap should go into Mysticism, not conjuration.

And then unto another topic, we shouldn't have lost the many spells we lost. We should had kept them and should have added more. As well.

A great illusion spell would be something like:

Horror- Terrifying visions rend an enemy's mind, leaving the target stunned inflicts recurring spirit damage for as long as the enemy remains stunned.

Mysticisms:
Shimmering Shield- The mage is surrounded by a shimmering shield of energy that blocks most damage and grants large bonuses to armor and all resistances. When active, however, the Shimmering Shield consumes mana rapidly.

Instead of taking away more should have been added. And mysticism should have never been taken away.

But m'aiq is very practical and has no need for mysticism.

Why would mage skin go to mysticism? What would "shield" spells be then?

There is still no real explanation as to why they removed it, aside from dumbing down the game by removing potentially complex options.